Wave transmission amplifier



Allg 26, 1952 c. c. CUTLER ETAL 2,608,623

vWAVE TRANSMISSION AMPLIFIER Y Filed June 1S, 1949 .2y sHEETSfsHEET 1 decor-Ek WENTO W E MA THEWS SHEETS- SHEET 2 C. C. CUTLER BVWEMTHEWS w l 7;. Arm/wry N m wm w C C CUTLER ETAL WAVE TRANSMISSION AMPLIFIER /NVE/vrons Aug.- 26, 1952 Flled June 18, 1949 Patented Aug. 26, 1952 WAVE TRANSMISSION AMPLIFIER Cassius C. Cutler, Gillette, and Warren E. Mathews, Chatham, N. J., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application June 18, 1949, SerialNo. 99,912

This invention relates to Wave transmission and more particularly to a novel means and method of amplifying a` transmitted wave of energy.

In the observation and measurement of various types of oscillation, for, example, the vibration measured in seismographic observations or the low frequency sound waves recorded in cardiographich'observations, it is often necessary to substantially amplify the desired energy oscillations before they may be observed or` recorded. `In such a case, it has been the practice to transform these oscillations into electrical impulses which impulses 'are then amplified by means of thermionic amplifier circuits. Great diiliculty has been experienced in the design of a thermionic amplifier suitable for'broad band amplification of the low frequencies encountered in these oscillations.

It is therefore an object of the invention to amplify sound waves, or other `vibrations, directly without conversion to electrical impulses.

Another object of the invention is to produce gain in a low frequency electrical signal of broad band width without the use -ofv thermionic ampliiier tubes and the inherent band width limitations of the circuits used therewith. Y

It is a further object of the invention to amplify pressure-or vibration wavesin a hydraulic or mechanical-,transmission system.

It is a feature of the invention by which the above-mentioned objects are accomplished to transform energy of uniform mechanical motion to energy of oscillationin atransmitted Iwave.

In accordance with the objects of the invention i an input signal to be amplified constitutingelectrical waves, mechanical vibrations, or hydraulic waves are impressed on a transmission medium coupled for mutual wave energy exchange to a second transmission medium moving relative to the first medium at a velocity related to the propgation velocities of wave transmission in the respective transmission media. The wave energy is amplified by a transformation of kinetic energy of uniform motion to energy of oscillation inthe respective waves. Y

In a rst embodiment of the invention electrical energy is amplified by the interaction of two coupledelectrical transmission lines in relative motion. In a second embodiment of the invention mechanical vibrations are amplified bythe interaction of two mechanical transmission systems in relative motion. In another embodiment of the invention hydraulic waves, either longitudinal or transversal, are amplified claims. (ci. 179-171)v by means of relative motion between two coupled hydraulic transmission systems. I

The nature of the present invention, its various objects, features and advantages will appear more-fully upon `consideration of the various embodiments illustrated in the accompanying'drawings andthe following vdetailed description thereof. Y

In the dra-wings: i

Fig. 1 shows by way of illustration the basic elements and their physical relationshipsin accordance with the theory underlying the invention; i l

Fig. 2 shows an electrical wave amplifier;

Fig. 3 shows by way of explanation the transmission line equivalent of thesystem'of Fig. 2;

Fig. 4 illustrates by way of example a hydraulic amplifier in accordance with an embodiment of the invention;

Figs. 5A, 5B, and 5C' show three alternative cross-sectional arrangements of a hydraulic amplifier as represented by Fig. 4 and Fig. 6 illustrates by way of example a mechanical amplifier in accordance with an embodiment of the invention. l

Ink order to fully understand the principles of the invention, itis necessary to understand a few basic principles of wave motion. In order, therefore, to Vprovide a firm foundation from which to proceed to the specific embodiments to be hereinafter described, a few general comments with regard to Wave motion are deemed worthwhile.

When a disturbance is introduced into a physical medium such as a liquid, it is well known that the disturbance will spread orv propagate through the,` medium. The medium does not move as a whole, but some particular configuration of its particles does, while the particles themselves oscillate over very short paths. Most waves can be classified as either longitudinal or transverse. A longitudinal wave is one in which the vibrating particles move forward and backward parallel to the direction in which vthe wave is propagated. In a transverse wave, the particles vibrate at right angles to the direction of propagation. Electromagnetic wavesl of all :types are transverse waves and are transmitted by changes in the magnetic and electrical fields of the waves which correspond' to the particles in other transmission medium.`

Thus, the progress of any wave involves two distinct motions. The wave itself moves forward with constant speed, which means that the conguration advances equal amounts in equal periods of time. Meanwhile the particles of the :medium that convey the wave vibrate in harmonic fashion. The velocity at which the wave progresses through the medium, known as the velocity of propagation, depends upon the speed at which these particles can change their position, which in turn depends kupon inertia and stiffness of the medium. This velocity is determined completely by the properties of the transmission medium and does not depend upon either the frequency or the wavelength of the waves. Thus, the velocity of propagation of wave in any Vmedium may be expressed 1 l Y l ymeasure of inertiaXmeasure of stiffness Awherein measure means the amount of inertia or stiffness of the medium per unit length'inthe direction of propagation. In a mechanical system,Y the velocity of'propagation is'controlled by varying the mass and compliance-oi' the elements ofthe medium which arethe mechanical parameters determining the measure of inertia` and measure' of stiiness, respectively. In a `hydraulic system the velocity of propagation is controlled by 4varying the densityl andicompressability of the gas vor liquid media which are the hydraulic parameters determining the measure of inertia and measure of stiffness, respectively.

. For electromagnetic waves the speed of propagation is determined bythe speed at which the associated electric and magnetic fields may change. When `the waves are propagated through theatmosphereor througha low dielectric medium, the fields may change very rapidly andthe velocity of .propagation approaches that of the speed .of light. However, when the electromagnetic waves are propagated through a mel dium having any effective distributioniof inductance and capacitance, which are the respective electrical parameters .determining the measure of inertia and measure of stilness, the Arate .of the successive decayand building up of thefields is decreased. This is the action Yof the familiar electrical delay transmission lineV or a Simple low passif-liter network. Assuming that the reactive components of the line are very large compared to the resistive components of the line, the velocity ofpropagation in meters per-second 'o fj an vele'ctrrnnagneticjwave along an inductive and capacitive vtransmission line may be expressed in which L is ,the inductance per unit length of theline in henries per meter and Cis the capacitanceper unit length of theline in farads per' meter'. A complete derivation of this expression may be found in Southworth, Principles and Applications vof Wave Guide Transmission,r D. Van Nostrand, 1950, pages 39 through i4,l or in Shelkunoff, .Electromagnetic Waves, D. Van Nostrand, 1943, pages-188 through 196. It is thus seenhthat the velocity of propagation of electromagnetic waves through a transmission medium-may be made as slow as desired by choosing the appropriate inductance and capacitance of the elements composing the medium.

, Having thus reviewed -the basicv principles of wave propagation, vmethod and means for producing signal energy amplification in related propagation media will now be disclosed. In accordance with the invention, the signal energy to'be amplified is impressed upon a first energy propagating medium for transmission therein in a forward direction. A portion of this energy is transferred to a seco-nd energy propagating medium to induce in the second medium a corresponding signalA wave that is Vtransmitted therein in a backward direction. The two media are moved relative. to eachother-ata constant velocity. 1 The effective -lnieasure .of' .inertiaV and measure of stiffness of each of the media are chosen to provide a velocity of propagation for the energy in each of the media which is less than the relative velocity of motion between the media so that the forward wave and the backward wave move together at the same velocity relativeto the rst medium. It will be seen that this requires a relative motionl equal to the sum of the propagation velocities in each of the media. The

- signal energy so amplified is removed from one rwave Aenergy propagatingY media are shown,

wherein III represents a medium capable of `independentlypropagating waves either forward. i. e. to theright, or' backward, i. e. to the left, at a first velocity V1, 'and I2 represents ya medium capable V-of independently 'propagatingwaves either -forward'or backward with respect @to the medium at a second velocity'Vz. Medium I'I is considered vto be stationary and Vmedium I2 is assumed .to .have a velocity iV in thel forward diiectonlf However, it is'understood 'that' V. rep` resents ,solely the relative velocity betweenthe respective media softh'at either yone yor both 'of thelatter maybe moving. Both 3 propagating'.

media 'maybe of any type suitable for support g and "propagating wave energy," vFor examp e, theymay be fluid streams capable of propagating hydraulic Ywaves,i electrical `transmission ,lines capable of propagating electromagnetic waves, or mechanical transmission systems capable of propagating vibration waves. u l

Since the backward wave'in medium I2 is propagated at a particular velocity in the backwardfdirection with respect to the medium, andsin'cejthe medium itself is movedA 'in a" forward direction at a velocityV, it is 'evident that" if the velocity of motion is greater rthan theve'locity o f fpro'pfi y agation, the` backwardwave lin mediurn- I'Zwill appear to move in al forward' direction with respect to fixed medium l'I'I.V This apparentemetion will be termed the resultant 4velocityouf-the backward wave in medium I2. Further, if-the velocity of motion V of medimY I2 is approximately lequalto V1+V2,`the resultant velocity yofthe backward wave in medium I 2 will beequalitothe velocity of the forward waverin'mediumII.

.Ifrth'e media II and I2 are. now related by coupling means, uniformly distributed along the length of the lines: for mutual wave energy transfer between the two media, the coupled systemis capable of supportinganyforl all of four'waves corresponding approximately to the natural waves vinthe absence of coupling. The energy of each of the waves present dividesinsome characteristic ratio betweenlthe two mediapgDu'e to the coupling, however, the propagation :behavior of these possible waves is somewhat different from the propagationrv behavior of the corresponding possible independent'waves in the absence of coupling. Inparticular,V whenV is approximately equal to Vi-I-V, orwh'en the rela- VV tive'A velocityv orme-tion between. the twov coupled transmission media-,is equal to the sum ofitiie Under `this condition, it has been found that one of the possible forward waves of the coupled system has an amplitude changing exponentially with distance and increasing in the forward direction providing amplification.

It has further been found that if an input signal is introduced at any point A along the system,"this energy will divide between the systernsand propagate away fromthe driving point byf'means'fof some `or"al l of thefour possible waves. At a .sufficient distance, which inall practicalapplications will amount to at least several wavelengths' of the input signal in the forward direction from the driving point, however, theincreasing wave will predominate over all others in the system and Valso will have an amplitude greater than that of the input signal. Thus a device of such length will serve as an amplifier of wave energy. The amount of this amplication as related to the velocities and coupling will be shown indetail later.

. Fig.' 2jshows an electrical wave amplifler. in whichthe foregoing principles` of operation are utilized, A'rotor core I4 Ais mounted for rotational motion within the stator` core I5. The structure" and relation `of these core pieces may be similar tothat employed for the common induction motor or otherrotating electrical machine, in which 'the stator, and rotor are provided witlipole-pieces Z'I'and 28l on which turns ofA Wire' maybe placed.. On the pole-pieces 2`I of the-stator are placed turns of wire which make up a plurality of inductive elements I6 connected in series. Capacitive elements I1 are connected between each of the .inductive elements I6 and a common point. This results in an electrical delay line having a velocity of propagation determined by the :valuelof the inductive and capacitive, elements IB and I1, respectively. A signal wave impressed upon the delay line by means of input terminals connected to one of the inductive elements I6 and the common connection of capacitive elements I1 will travel around the delay line and may be taken from the delay line by means of output terminals 2I connected between the last of the series inductive elements I6 and the common connection. An impedance element 22 is provided across the output terminalsv `2| for matching the characteristic impedance of the stator delay line to the connected output system to prevent reflections back along the stator delay line from terminals 2I` toinput terminals 20. A similar electrical delay line is placed on the rotor comprising inductive elements I8 wound on pole-pieces 28 of rotor core I4 and connected in series to form a closed loop,` Vrather than open and terminated as the stator delay' line is, and capacitive elements I9 whichare connected between a common point and the connection point between each of the inductive elements I8. This provides a second delay line having a velocity of propagation determined by the value of inductance and capacitance of elements IB and I9, respectively. A commutator of standard construction and a' slip ring 24 also of standard construction are arranged to rotate with the rotor in the usual manner. The commutator segments 23 are each connected to the point of connection of adjacent inductive elements I8 and capacitive elements I9 of'the rotor delay line. Slip ring 24 is connected to the common connections of capacitive elements I9.

The core structures I4 and I5 may be constructed ofV magnetic material, which @would naturally increase the effective inductance of inductive elements I6 and I8, or these structures may ber constructed of non-magnetic or dielectric material which provides a rigid support for the inductive and capacitive elements without affecting the Vvalue thereof.

The rotor I4 is driven to rotate at a constant velocity in the direction of propagation from in put connection 20 to output connection 2|, or as shownlcn Fig. 2, in a clockwise direction by a prime mover of any type. VAt a point. slightly .in advancefofxinput connection 20 .with resi JectltoL this rdtation, ,a brush 223 islocatedlj makes successive contact with each of mutator segments '23 as the rotor rotat contatitfZS` and resistor 26 'are connecte slip rin'g24 Vand brush 22. This slip rin resistor, combination discharges each section Y of the rotor delay line as it passes the position of brush 22 so that at the time the shorted section passes'a point adjacent input connection 20 it will contain substantially nov signal energy; The purpose of this circuit will later become apparenti The operation of the electrical wave amplifier of Fig.A 2 may more readily be analyzed with refererice' to Fig. 3, wherein the stator delay line is represented by line 3I and the rotor delay line by; line 32 with the discharging connections 22, V25'and 26 in the proper relative position. The rotational velocity'of the rotoris :indicated by "a relative ',velocityVi between lines 3 I fand! ,32.

In Fig. 3, L1 and C1 are the series inductance and shunt capacitance per unit length of line 3|, either uniformly distributed or distributed in discrete sections short compared to the wavelengtltat the operating frequency. L2 and Cz are the corresponding elements of liner32-and the two lines are coupled by means of a mutual inductance Lm per unit length.

The uncoupled wave propagation velocities oi' the two lines are given by therelations defined above where pling parameter a is definedVv as L The coupling between the systems rniglit'well` be capacitive ratherA than inductive as indicated.

The? behavior of the coupled system at any point'along the linesmay be described by the thepropagationvelocity of line32; andthe equations and where-the instantaneous line currents i1 in line' theisame.,timeandispaeevariationsgin. anyone 'Y z i'zgfinstntaneoseline, voltages,;.'en and ez: fhave been;aannnedfto".betet?thezlibrm1 "f ,header-ide v presentthe V'corrersrinonfding quantities ien with?. #hemmt ef reference mevee; rite trarne ofgrefereneeit ,fellows:thatl g and; expanding-,Kimi `in ,a;,-.Taylor sexiest.' there results: v

The.. parameteris' ,.a-. measure.. ef; theydeviat'on n frornequality betweenthenatural forward ware; velocity/didine 3.! vand theflreeultant natural. backward .wave v.elocit'yv...of. line 3 2.- Solution. oi

Equation.` 19 for and. substitution. into Eq'ar' tionI 118 yields, witn thema. QfiEquatiqn .120@

3 'liese two yal-ues.; ofY Ythe; propagation characterize two', "of the pczsslible;iillajves;` of." the eeupied. System whenV (Vivar 'is' 'appreximatem equal to Vi'. When 6:50; crm-is' ysufficiently jsmall Ithat `2'--,#V',-#V'1V2 0 thenfi fand'. 132 @Xe Comi-Q Plex, .characterizing .respectivelythe increasing. f

Wave .mentined .previouswl and; azdeereasna QIII'; 1?y case, the vrate of increase Yof the line' ereasingiwave.eorrespvndinaite temprana.- gatonle ii'gja .nathlengthfequal Qnegwavee length., ofjrthe@ signal; beinef'ihi21iedl-is.' given by. j

nialihg-use ofEdu'a'tion 1'3- to'leliininate thermof- Eqllatln iS. Equally Vvalid when f the coupling between lthe lines is.eaiiaitive, inw-hiel; ease A i i A.

fi tja-e,

where; Gm.` is.- the `mutualV eapaeitance L.per unit Ihg'tha. ,g I

Cal

obviously are the resultant uncoupled mode propagation constants. Setting givenV approximately@ byjf Y approximately by t periphery of rotor. L4. thus niovesat aVelocityfS/ of 290D, centimeters per second. lffhepreagation velocities V1; and. Veuf. the. signal, Waves" on. the stator line f3 I .andv roto-r lineV respectively, 5 are equal and are, therefore, Vequal-to; LOQOQcentiinee ters per; secondor 10. meters pensecpnd. In

accordance with Equations 4 1 1 and 2.- aliove; the- Y product-vof LC necessary tc-givefthis propagation velocity for ,Vr and is. 0.01.1.,henryaradfvpeig square-- meter. l A transmission Y lineernpedanceiof llflfih'ohmsT isi. obtained by proportioningthe inductance A and .capacitance -Y as', 1.070,. henr'iesQ-per meten. and .100 mierofarfadsper ,metergv respee.- tively. Since the outside circumferencefof rotor ltfis. 50;centime ters-. Qf li) wavelengths, 5 0,

tive elements I3, each having an inductance of lhenry, and 50 capacitive elements i9, each having a capacitance of l. microfarad, are employed, al1 equally spaced 1 centimeter or 0.2 wavelength apart. The same number and size inductive elements; I3 `and capacitive elements I1 are located atthe same interval around stator l5. Y

lhus the electrical Wave amplifier of Fig. 2 provides gain per unit length around its circumference.` The signal introduced by line 20 is mutually propagated by the stator and rotor transmission lines 3l and 32 around the circumference of the system at a velocity of 1000 centimeters per second. This mutual propagation amplies .the signal whenrthe. rotationalyelocity of the rotor i4 with respect to the stator `I5 is equal to approximately 2000 centimeters per second, the sum'of thepropagation velocity of the signal around the stator in the absence of coupling and the velocity of the signal around the rotorA in the absence of coupling.`. The ampliiied signal is taken off by transmission line 2 I. Thev slip ringbrush resistor combination 23, 22 and 25 dissipates the energy on the rotor delay line 32 at the' end of one revolution by short-circuiting this line through resistance 26 having an impedance Vof ,1000 ohmsl at a point opposite or in advance of 'the transmission line20, thus preventing feedback'of the ampliiied wave energy to the input of the device. The ,dissipated energy may be used if desired as a secondoutput by connecting the desired load across resistance 26.

Referring nowto Fig. 4, a'hydraulic amplifier is illustrated comprising a substantially inflexible outer cylindrical container 35 and an inner container 35 extending'v therethrough.` The inner container is provided with a flexible wall 31 which wall extends along the portion of tube 36 included 'within cylinder 35. The system is filled with iiuid. "Bothcontainers 35 and 36 may contain `th'esame fluid 'orvthey'may contain fluids having 'different'wave propagation velocities. The fluid in the inner container 36 is forced from tank 38 by a highV velocity pump 39 through connecting tubes 40 and 4I. The fluid in cylinder 35 may be stationary and is connected through branching pipe 42 and tube 43 to a diaphragm 44. For

example, diaphragm 44 may be a portion of the ,inner pipe 36 is forced through the system with Vthe `velocity V equal` to the sum of the respective natural propagation velocities of the iiuids in cylv`inder 35 and cylinder` 36, thus producing maxi- :mum amplification inthe direction of motion of .theinner stream. The lvalueof this amplificatonis expressed byEquation 25 Where c is the `coupling between thestreams provided by the ,membranous wall'31 and V1 and V2 are the natural propagating velocities ofy the'outer stream :and inner stream-respectively. The mechanical .vibration applied-through connection 42 to the fluid in cylinder, 3,5 will be.` amplified overthe -flenethiicf .zthgmutual .propagation Ynath and transmitted, from the 'amnlienbv means 0f piston 45 located inconnection 46 `and making con- `tacij, -,with,the iiuidn cylinder35,'and the linkage .mechanism .41.. to ze :vibratcn utilizing mechani sin46.. Klvlechanism481sv shown by way of illus- 10 tration as the stylus of a vibration recording device 49. Signal energy remaining in the inner stream will pass out through pipe 50 and will be dissipated inreservoir 38 or, as in the case of the electrical system, this dissipated energy may be used as a second output.

In order to prevent undue reflections within the iiuid, reflection absorber 5| is placed in the output end of cylinder 35 to absorb vibrations. Absorber 5| may be a wedge of dissipating material such as soft felt or rubber which can readily absorb vibrations. Without this reflection absorber it is readily apparent that the amplifier would become self-oscillatory.

However, should it be desired to generate oscillations, absorbing material 5I as Well as reservoir 33 may be eliminated and pipes 40 and 5|] connected directly together. Thus all vibrations would be retransmitted to the input thus pro-viding positive feedback and self-sustained oscillations. oscillatory energy may be taken off from either connection 46 or connection 42.

The hydraulic waves thus far considered in Fig. 2 are well known in the artas compressional or longitudinal Waves. The propagation velocity of such Waves depends on the elasticity and density of the medium; `the greater the elasticity or the smaller the density, the greater will be the propagation velocity. Therefore, substances such as Water will have a much greater propagation velocity than substances such as mercury or oil. For this reason, the fluids contained in cylinders 35 and 36 may be chosen to have a low velocity of propagation and therefore substantially decrease the velocity of iow that is required to obtain maximum amplification.

Fluids also lmay transmit transverse or surface waves in which the particles of the medium move at right angles to the direction in which the wave is propagated. In general, transverse waves are propagated at a much smaller velocity in a given substance than the longitudinal waves. The velocity of the former depends to a large extent on the restoring force on the wave, i. e., the weight of the fluid and its surface tensionl in an open container. The smaller the restoring force or the greater the effective compressibility of the uid medium the smaller is the velocity of. propagation.

The cross-sectional views of Figs. 5A through 5C represent alternative arrangements of the two streams as described with relation to Fig. 4, wherein the slower moving or transverse wave is utilized by the inclusion of aresilient or highly compressible medium to increase the effective compressibility of the fluid media.

In Fig. 5A, cylinder 35 is shown as divided into three cross-sectional segments. The media contained in segments 52 and 53 are separated by the membranous wall 54 and either or both may be moving to provide the proper relative velocity. Segment 55 may be iilled with air, vacuum, or any other resilient medium to provide the desired restoring force.4 In Fig. 5B the cylinders containing the propagating media 52' and 53' are arranged one within the other and the resilient medium 55' may be concentric there.- about or eccentric Aas shown. In Fig. 5C the `tvvo streams 5B and51 are indicated as being laterally contiguous'with a separate restoring medium 459 for each'jstream.` The arrangements thus shown are merely. suggestive of possible configurations and` numerous others Will serve equally well. For example, the two streams may be sim- 11 ply open troughs which are coupled through a common exible boundary.

Fig. 6 shows an amplifier for the amplification of mechanical vibrations comprising two identical mechanical wave transmission systems capable of relative mot-ion therebetween and coupled magnetically for mutual wave energy exchange.

Each transmission system comprises a wheel 6i having radiating spokes 62. Around the ends of spokes 62 is placed a hoop of flexible spring material 63 supported and held in place by the spokes ll? but not rigidly connected thereto. This connection is such as to restrain the hoop 63 in a direction tangential tothe hoop circumference so that the rotational motion of the wheel BI and the spokes (i2 'will be imparted to the hoop 63.` This connection, however, must allow the spring hoop 53 to be free to twist or to be free for partial rotation of a segment thereof about the tangential axis. Around the periphery of the hoop are located bars S4, relatively massive with respect to the mass of the spring material of hoop 63. Bars 64 are mounted rigidly to hoop 63 at` equally spaced intervals and extend transversely`v on either side of the hoop perpendicularly tothe tangential" axis. Anydisturbance introduced upon one of the vmassive bars E4 tending to rotate the bar about the tangential axis and thus to ltwist the portion of the hoop 63 immediately adjacent thereto, will be transmitted from bar to bar `around the system by the torsionalvaction of the interconnecting spring "63 at a velocity of propagation depending upon the spring material.

The two systems are axially mounted andeither or both are cap-able of rotational motion. A prime mover A65. is shown for rotating the system o-n the left at a constant angular velocity. 1 Vf At the ends of the bars 6.4 are mounted radially oriented permanent magnets 66.. and x6?. on the bars ofthe first system, and magnets 68 Vand -69 on the second system. Magnets 6,'6 and 61 are polarized in `one direction and '68'.and. 69 in the opposite direction so that the strongest possible coupling force may "be obtained between the closely spaced magnetsl and 68 between the two systems. A wave introduced on one of the systems will therefore be coupled through the mag-nets to the other system;

Numerous meansfor introducing an initial dise turbance may be devised dependingon the system to 4be connected. One. possible means is shown in Fig. 6 vwherein amagnet H is mounted on support l2inlclose proximity to the magnets .6.9. Any movement of 'H coupled thereto bydar linkage mechanism from a vibration input source Vll will therefore. be imparted by magnetic attractionor repulsion tothe magnet opposite it which will take up like motion. This motion will be imparted toA thenext bar 64 by means of. the connecting spring` member 6 3 and thus to the. following bar vand successivelyY around the perimeter .of the spring until the wave motion reaches damping wheels 'I3 and 14., Damping members l3and I4 are 'placedv toi'roll-upon the surfaces of bars '6.4 at a point in advance,` with respect to the direction of rotation, of the bars 64 coupled magnetiinstant is making contact with it'. j, It is pointed out that damping wheel13serv'es affunction analmass of the bars and vthe compliance of the y lic system or the shorting resistance '2S in Fig, 2

of the electrical system, while damping wheel 1 4 i is analogous to the absorber 5I in Fig.'4`.

V.lita point precedingdamping' wheels 13 and i thereto by the magnetic coupling of 69 to l5. An

output -mechanism 'I6 is shown connected'to magnet '15 similar tothe output mechanism 48 of Fig. 4. Y

'If one or both of the transmission systems are turnedfs'o' that there is aconstant relative motion-between themequal tothe sum of their natural-propagating velocities, ampliiication will result fromv the wave interactionl between the-sys A tems around the perimeter ofthe wheels. A lsmall disturbance or signal vibrationV introduced by'll will be amplified and taken from the system 4It is readily apparent that the input signal energy may be impressed oneither of the systems andl that the output signal may be taken from either or bothof the systems. Likewise, it is apparent that either system may move or that both'may move in such a manner in either case that substantially the desired relative velocity between the systems is preserved. As in the case of the hydraulic *and` electrical systems, various means of' coupling between the mechanical systems may/be employed. For example, a. system of rollers,r and springs .might be used rather than the system of magnets vas shown. l

It is' to be understood that the above arrangements are illustrative in the specic embodiments thereof of the principles of .the invention.

Numerous other arrangements may be devised by the spirit and scope of the invention.

Whatis claimed is: .l. lIn combination, a pair ofguided wavetransmission systems in ,distributedY intercouplin-g rethose skilled in the art without departingfrom lation to each other, driving meansto move one f of said systems continuously relative to theotlier y at a constant relative velocity, input meansto excite a signal wave in one of said systems for transmission'therein in the direction of relative motion'of the other of said systems, means inducing in said other system a corresponding. sig- 'equals'. said constant relative velocity, whereby both said excited wave and said induced Wave are transmitted in the same direction with sub'- stantially the same velocity relative'to saidrst systempand output means coupled to at leastone of said systems for abstracting the resultant am- "p'lifledA signal wave.

32. The combination in accordance with claim I, wherein'each of saidpair of guided Wave transmission systems 'isil a two-conductor yelectrical delaytransmissionline and wherein said-inter- 'coupling'is r'eactively provided between'saidlines l.

along faportion o f their length.A i

l' a The eombinatinfin accordanceffwitnclaim` 1,"wherei'n`each`of said pair of guidedwave-transarcanes cluding a membranous -wallseparating said media to ,provide'said intercoupling. t

4. The combination in accordance with claim l, wherein each of saidY pair of guided wave transmission systems is afluid'medium and including means for increasingthe effective om; prssibility of said` media; 'is 1- i 5:;

:;5. The l,combination in accordance with claim 1;`wherei.n each of said pair of guided Wave transmissionsystems is a mechanical ,vibration transmission meansand wherein said intercoupling is magnetically"provi` ded between said systems. 6; A- Wave amplifyingsystem `comprisinga first wave energy propagating medium, signalinput means for exciting a wave of energy in said medium to be propagated therein in a first direction, a second wave energy propagating medium, wave energy transmission means coupling said rst and second media for mutual wave energy exchange therebetween along an effective length for said wave energy of several wavelengths in said propagation direction, means for producing motion of one of said media relative to the other of said media at a constant velocity therebetween, said rst wave propagating medium having a wave energy propagation velocity less than said constant velocity, said second medium having a Velocity of propagation for the wave energy therein substantially equal to the difference between said constant velocity and said propagation velocity of said first wave energy propagating medium.

7. An amplifying system in accordance with claim -6 for electrical waves, wherein said iirst and second propagating media each comprise a two-conductor electrical delay transmission line and wherein said wave energy transmission means comprises reactive coupling between said lines.

8. An amplifying system in accordance with claim 6 for electrical waves, wherein said first and second propagating media each comprise a two-conductor electrical delay transmission line of inductive and capacitive elements and wherein said wave energy transmission means comprises inductive coupling between the inductive elements in one line and the inductive elements in the other line.

9. An amplifying system in accordance with claim 6, wherein said first and second propagating media comprise contiguous fiuid transmission means and wherein said wave energy transmission means comprises a membranous wall separating said uid means and is adapted to transmit waves therebetween.

10. An amplifying system in accordance with claim 6, wherein said rst propagating medium comprises a rst liquid stream, wherein said second propagating medium comprises a second liquid stream located contiguous to said first stream, wherein said wave energy transmission means comprises a membranous wall separating said first and second streams and is adapted to transmit waves between said streams, and wherein said means for producing motion comprises a source of hydraulic potential associated with one of said streams to force said stream to flow at said velocity relative to said other stream.

1l. An amplifying system in accordance with claim 6, wherein said first and second propagating media each comprise mechanical vibration transmission systems and wherein said wave energy transmission means comprises a plurality of magnetic means located at a plurality of points along each of said systems, the magnetic means A along. ,one` of said. `systems being located within the magnetic4 field .of t 1the 'magneticV means along the otheraoffsaidsystems.` L f i w `l2.An amplifying,..syste.m comprising a first wave energy propagatingmedium, a second wave energypropagatingmedium, said second medium coupledswithsaidzi'irstmedium for mutuaLwave energyfexchange-, 3` means for moving said second medium relative-,to saidflrst medium witha,` con-1 stant relative; velocity therebetween; Said ,l first propagating medium having a first wave propagation 4velocity `for ,wave energy therein less than. said relative constant-velocity, said second propagating medium having a velocity of propagation for the wave energy therein substantially equal to the difference between said constant relative velocity and said propagation velocity of said first wave energy propagating medium.

13. An amplifying system comprising a first wave energy propagating medium having a measure of inertia and a measure of stiffness, a

Vsecond wave energy propagating medium having a measure of inertia and a measure of stiffness, said second medium being coupled with said iirst medium for mutual wave energy exchange distributed over an eiective length as measured along said media for said wave energy of at least several wavelengths, means for moving said second medium relative to said first medium with a constant relative velocity therebetween, said measure .of inertia and said measure of stiffness of said first medium providing a wave propagation velocity for wave energy in said first medium substantially less than said relative constant velocity, said measure of inertia and measure of stiiness of said second medium providing a wave propagation velocity for wave energy therein substantially equal to the difference between said constant relative' velocity and said propagation velocity of said iirst wave energy propagating medium.

14. An amplifying system comprising a first two-conductor electrical delay transmission line having a value of distributed inductance and capacitance, a second two-conductorI electrical delay transmission line having a value of distributed inductance and capacitance, said second line being coupled with said first line for mutual wave energy exchange distributed over an effective length as measured along said lines for said wave energy of at least several wavelengths. means for moving said second line relative to said first line with a constant relative velocity therebetween, said value of inductanceV and said value lof capacitance of said first line providing a wave propagation velocity for wave energy in said first line substantially less than said relative constant velocity, said value of inductance and said value of capacitance of said second line providing a wave propagation velocity for wave energy therein substantially equal to the difference between said constant relative velocity and said propagation velocity of said rst line..

15. The method of producing signal energy amplification which comprises impressing signal energy to be amplified upon a first energy propagating medum for transmission therein in a first direction at the natural Velocity of propagation of said first medium, transferring a portion of the propagated signal energy in said first medium to a second energy propagating medium to induce in said second medium a corresponding signal that is transmitted therein in a direction opposite to said first direction at the natural v'eocity of prpgat'in. Qt'jsaid second mediumb y REFERENGES,GIEED dYeloPng-*cfnstam- IWW 10mn-,between The following"-Vefeences--are' uffreordmf-the saxd first medlumiad said secondfmedlum subme of this; ,pteff v l stantially-equaL-to.the sum Kofi the absolute 5 A* v. mmm:-propagauonve1acizies of samfmedia. 5v .A UNITED ,STA'ES' FATENTS e whreby said sighlalinlsaaic rstmediumvandf said Number f f ,Name v Date indtxcedfsignalare ptopgatedfnthesamedreci 1,289,574 Tedeschi.; f- Dec; "311, c1918 tinfamiI with substantially the same vvelocity 1,546,4`4f0` Fessenden; AH muy-'21?, 1925 relative-tofsadfrst medium, and remqving'said 1,125,662 Merrill: i-;a' :Aug.i20, 1929 f -rcassms c. CTHE REFERNCESW,

n ,y PublicatomHwfthq A mplidyvne Functions; I

. i' Y ElgctrcaLWorldi May l, IMS-P74 (1474). Y Y 

